The proposed program project on The Global Burden of Disease 2000 in Aging Populations is a coherent series of investigations that will strengthen the methodological and empirical basis for undertaking comparative assessments of health problems, their determinants and consequences in aging populations. Since the publication of the Global Burden of Disease Study 1990, there has been increasing interest in comparative analyses of health outcomes, determinants and consequences. The World Health Organization is committed to undertaking a major revision of the Global Burden of Disease Study for the year 2000. This program project would strengthen the scientific basis for this large-scale undertaking. It is structured around a core with an administrative, a data management and a methods component and eight projects: 1) measurement of adult mortality in the developing world; 2) non-communicable disease mortality transitions; 3) adapting statistical methods for public health research; 4) avoidable causes of adult chronic disease death; 5) self-reported and observed measures of health status; 6) the impact of co-morbidity on non-fatal health outcomes; 7) summary measures of population health; and 8) health costs of aging, present and future trends. The cor and the eight projects enrich each other through multiple mechanisms, including investigators working on a number of components, common datasets and methods development. A key strength of the program is the close partnership between the lead institution and the World Health Organization, assuring the close coordination of the research work in the program through key personnel. The principal investigator is both a Professor at Harvard and the acting Director of the Global Programme on Evidence for Health Policy at the World Health Organization. WHO personnel are project leaders on three components. An important goal of this project is to aging population, while at the same time strengthening the empirical and methodological foundations on which policy decisions are made.